1. Field of the Invention
The present invention relates to a valve timing control device for modifying the opening and closing timing of the intake and exhaust valves in an internal-combustion engine (hereafter, referred as an engine) according to any operating condition.
2. Description of the Prior Art
Conventional valve timing control devices are disclosed in JP-A-1997/280020 and JP-A-1999/210422, for example.
FIG. 1 is a perspective view of main points of the engine provided with the conventional valve timing control device mounted on an end of an intake camshaft. FIG. 2 is a lateral cross sectional view of an internal construction of the conventional valve timing control device of FIG. 1. FIG. 3 is a longitudinal cross sectional view taken along lines Axe2x80x94A of FIG. 2.
In the drawings, reference numeral 1 denotes a crankshaft (not shown) of the engine, and 2 denotes an intake camshaft integrated with a cam 3 controlling an open/close timing of an intake valve 4. 5 denotes an exhaust camshaft integrated with a cam 6 controlling an open/close timing of an exhaust valve 7. 8 denotes a valve timing control device (hereafter, referred as device) mounted fixedly at one end of the intake camshaft 2, 9 denotes a sprocket mounted fixedly at one end of the exhaust camshaft 5, and 10 denotes a sprocket mounted fixedly at one end of the crankshaft 1. 11 denotes a chain which acts as an endless transfer member wound around the sprocket 10, the sprocket 9 and a sprocket described later of the valve timing control device, turning clockwise (direction of arrow CW) in the drawings. A slit 2a is formed at the other end of the intake camshaft 2, and a slit 5a is formed at the other end of the exhaust camshaft 5. The slits 2a and 5a allow engagement of a positioning spacer 12 resulting an angle defined between the both camshafts.
Hereafter, the internal construction of the valve timing control device will be explained. In FIG. 2 and FIG. 3, 13 denotes a first rotor which connects with the crankshaft through the chain 11 to rotate in synchronization with the crankshaft 1. The first rotor 13 includes a sprocket 14 rotating in synchronization with the crankshaft 1, a case 15 having a plurality of shoes 15a which are projected from an inner portion of the case 15 to constitute a plurality of hydraulic pressure chambers, a cover 16 covering the hydraulic pressure chambers, and a threaded member 17 such as a bolt and so on integrating the sprocket 14 and the case 15 with the cover 16.
A rotor (second rotor) 18 is arranged within the case 15, and allows the relative rotation with respect to the first rotor 13. The rotor 18 is fixedly integrated with the intake camshaft 2, which relates to open/close operation of the intake valve 4, through a washer 19 by using a threaded member 20 such as a bolt and so on. The rotor 18 has a plurality of vanes 18a dividing the hydraulic pressure chambers, which are constituted by the shoes 15a of the case 15, into an advance side hydraulic pressure chamber and a retardation side hydraulic pressure chamber 22. Moreover, a first oil path 23 and a second oil path 24 are arranged within the intake camshaft 2. The first oil path 23 supplies hydraulic pressure to, and discharges a hydraulic pressure from the advance side hydraulic pressure chamber 21. The second oil path 24 supplies hydraulic pressure to, and discharges a hydraulic pressure from the retardation side hydraulic pressure chamber 22.
Seal means 25 are arranged on both of front ends of the shoes 15a of the case 15 and the vanes 18a of the rotor 18, respectively. The respective seal means 25 includes a seal member 25a for sliding on an inner wall face of the advance side hydraulic pressure chamber 21 or the retardation side hydraulic pressure chamber 22, and a plate spring 25b for biasing the seal member 25a toward the inner wall face.
An accommodation hole 26 is arranged at one of the shoes 15a of the case 15 acting as the first rotor 13. A lock pin 27 having a cylindrical shape is accommodated in the hole 26 to restrict relative rotation of the first rotor 13 and the second rotor 18. Incidentally, since hydraulic pressure in the valve timing control device is reduced on starting the engine, the rotor 18 vibrates in the rotational direction by a cam load applied to the cam 3 integrated with the intake camshaft 2. When the first and second rotors 13 and 18 repeat contact and separation, and beat noise (abnormal noise) necessarily results. The lock pin 27 prevents the occurrence of the beat noise (abnormal noise). The lock pin 27 also keeps a required angle between the first and second rotors 13 and 18 under low hydraulic pressure being difficult to control the angle. Therefore, the lock pin 27 is biased by an biasing member 28 such as coil springs to engage in an engagement hole will be explained later, the biasing member 28 being arranged between a rear wall of the accommodation hole 26 and the lock pin 27.
On the other hand, an engagement hole 29 is formed at the rotor 18 acting as the second rotor to allow insertion of the lock pin 27 when the first rotor 13 is positioned with respect to the rotor 18 at a required angle (maximum retardation).
A release valve 30 is arranged at the shoe 15a. The release valve 30 supplies selectively the higher hydraulic pressure in the advance side hydraulic pressure chamber 21 and the retardation side hydraulic pressure chamber 22 to a release hydraulic pressure chamber 99 to release engagement (hereafter, referred as lock) between the engagement hole 29 and the lock pin 27. The release valve 30 communicates with the release hydraulic pressure chamber 99 through a release hydraulic supply path 31. The release valve 30 and the advance side hydraulic pressure chamber 21 communicate with an advance side pressure partition path 32, and the release valve 30 and the retardation side hydraulic pressure chamber 22 communicate with a retardation side pressure partition path 33.
A recess 35 is formed at the rotor 18 acting as the second rotor to engage with a knock pin 34 which is arranged at one end of the intake camshaft 2 to define a relative rotation between the device 8 and the intake camshaft 2.
Next, a method of assembling the valve timing control device will be explained.
At first, the valve timing control device is arranged at one end of the intake camshaft 2. Here, the lock pin 27 is engaged with the engagement hole 29 to position fixedly the first rotor 13 of the device 8 and the rotor 18 acting as the second rotor at the required angle. The knock pin 34 of the intake camshaft 2 is further engaged with the recess 35 of the rotor 18 to position fixedly the intake camshaft 2 and the rotor 18, in other wards, to fix the device 8 at a required angle. The sprocket 14 is connected fixedly to the rotor 18 positioned at the required angle by the threaded member 20 to position fixedly the sprocket 14 and one end of the intake camshaft 2.
Next, the sprocket 9 is arranged at one end of the exhaust camshaft 5. Here, a knock pin (not shown) of the exhaust camshaft 5 is engaged with a recess (not shown) to position the exhaust camshaft 5 and the sprocket 9 at a required angle. The sprocket 9 is fixed to the one end of the exhaust camshaft 5 by a bolt (not shown).
Next, as shown in FIG. 1, a crank-fixing pin 36 is screwed into the crankshaft 1 from the outside of the engine to position the crankshaft 1 at the required angle. The positioning spacer 12 is inserted into the slit 2a of the intake camshaft 2 and the slit 5a of the exhaust camshaft 5 to regulate the angle defined between the both camshafts.
Next, the chain 11 is wound around the sprocket 10, the sprocket 9, and the sprocket 14, and is then held under a tension by a chain-tensioner (not shown) in order to prevent the slack of the chain 11. In this state, the sprocket 10 is fixed to the one end of the crankshaft 1 by the bolt (not shown).
However, the conventional valve timing control device having the construction above may display assembly errors in fitting the device on the engine resulting from looseness between the lock pin 27 and the engagement hole 29, between the knock pin 34 of the intake camshaft 2 and the recess 35 of the rotor 18, and between the knock pin (not shown) of the exhaust camshaft 5 and the recess (not shown) of the sprocket 9. Thus, there is a problem that a gear with respect to the intake camshaft 2 is not timed to a gear with respect to the exhaust camshaft 5.
Accordingly, it is an object of the present invention to provide a valve timing control device, which allows assembly with minimum numbers of errors and allows simple fitting into the engine.
In order to achieve the object of the present invention, a valve timing control device comprises a first rotor rotating in synchronization with a crankshaft of the engine, the first rotor having a plurality of shoes inside thereof; a second rotor fixed on an end of an intake camshaft or an exhaust camshaft of the internal combustion engine and arranged rotatably in the first rotor, the second rotor having a plurality of vanes on the outside; an advance side hydraulic pressure chamber and a retardation side hydraulic pressure chamber defined between the vanes of the second rotor and the shoes of the first rotor; a lock member locking the first and second rotors at a required angle which the second rotor forms with the first rotor; an engagement hole arranged at any one of the first and second rotors to allow insertion of the lock member; and a chuck site being chucked by a chucking tool used for fitting the actuator to the engine, which is arranged at least one on the first rotor or on the second rotor. Thus, the valve timing control device can be supported rotatably by the intake camshaft or the exhaust camshaft to do assembly with a minimum number of errors with respect to fitting the device to the engine. Moreover, a time lag in open/close timing of intake and exhaust valves can be resolved which allows simplification of assembly work, in particular auto-assembly work.
The chuck site may be arranged on the first rotor, allowing the engagement of the chucking tool operated in a radial direction of the first rotor. Thus, the device can be easily supported through the chuck site of the first rotor to perform the simplification of the auto-assembly work.
The chuck site may be arranged at an outer circumferential portion of the first rotor. Thus, since the chuck site is arranged at a position keeping a distance from an inner portion subjected to a hydraulic pressure, the first rotor can maintain high mechanical strength.
The chuck site may be arranged on the first rotor, allowed to insert the chucking tool which is operated in an axial direction of the first rotor. Thus, the device can be easily supported through the chuck site of the first rotor to perform the simplification of the auto-assembly work.
The chuck site may be a bolt head used for assembling the actuator. Thus, the device can be easily supported through the chuck site of the first rotor to perform the simplification of the auto-assembly work.
The chuck site may be arranged on the outer circumferential portion of the first rotor, and may have a polygonal shape. Thus, a simplification of the shape of the first rotor is possible. Since the chuck site is arranged at a position keeping a distance from an inner portion subjected to a hydraulic pressure, the first rotor can maintain high mechanical strength.
The chuck site may be arranged on the outer circumferential portion of the first rotor, and may include at least one plane. Thus, a simplification of the shape of the first rotor is possible. Moreover, the device can be easily supported through the chuck site of the first rotor to perform the simplification of the auto-assembly work.
The chuck site may support the first rotor or the second rotor in a rotational direction thereof. Thus, the device can be easily supported through the chuck site of the first rotor or the second rotor to simplify the auto-assembly work.
The chuck site may be arranged on the outer circumferential portion of the first rotor, and may have a groove to separate the chuck site from an endless transfer member transferring rotation of the crankshaft. Thus, the endless transfer member can keep from contact with the chuck site of the first rotor having a small radius.
The chuck site may be arranged on the inner circumferential portion of the second rotor, and has a polygonal shape. Thus, a time lag in open/close timing of valves owing to a threading torque can be resolved. Moreover, when the device above is arranged on one of the camshafts, a device having a chuck site arranged at a first rotor is arranged on the other to do assembly of the both devices with a minimum number of errors with respect to fitting the respective devices to the engine.
The chuck site may be arranged on the second rotor, allowing the engagement of the chucking tool operated in a radial direction of the second rotor. Thus, a time lag in open/close timing of valves owing to a threading torque can be resolved. Moreover, when the device above is arranged on one of camshafts, a device having a chuck site arranged at a first rotor is arranged on the other to do assembly of the both devices with a minimum number of errors with respect to fitting the respective devices to the engine.
The chuck site may be arranged on the second rotor, allowed to insert the chucking tool which is operated in an axial direction of the second rotor. Thus, a time lag in open/close timing of valves owing to a threading torque can be resolved. Moreover, when the device above is arranged on one of camshafts, a device having a chuck site arranged at a first rotor is arranged on the other to do assembly of the both devices with a minimum number of errors with respect to fitting the respective devices to the engine.